Communications systems typically require a use of multiple printed circuit boards housed on various shelves within a frame or rack. Various printed circuit boards control different functions and are required to communicate with boards on different shelves and with boards located at different frames. Typically, high level data commands generated by master microprocessors are required to communicate with lower level functions found on multiple cards.
Where a slave card is malfunctioning, it is necessary to determine whether the card is malfunctioning in order to take corrective action, such as resetting the card or disabling the slave card to prevent jamming of the communications bus between the master card and the plurality of slave cards. A resetting of a slave card may require separate communication paths to each card which results in a multiple wire cable for the disable or reset function.
A need has thus arisen for a control bus having the ability to selectively enable or disable slave to master communication and to reset slave cards.